cores: Fix Serial.

Signed-off-by: zhanglinjing <[email protected]>

Author: LinjingZhang

cores/HardwareSerial.cpp

@@ -32,7 +32,6 @@ HardwareSerial::HardwareSerial(XMC_UART_t *xmc_uart_config,
                                RingBuffer *tx_buffer) {
     _XMC_UART_config = xmc_uart_config;
     _rx_buffer = rx_buffer;
-    _tx_buffer = tx_buffer;
 }
 
 // Public Methods //////////////////////////////////////////////////////////////
@@ -118,12 +117,7 @@ int HardwareSerial::available(void) {
     return SERIAL_BUFFER_SIZE - _rx_buffer->_iTail + head;
 }
 
-int HardwareSerial::availableForWrite(void) {
-    int tail = _tx_buffer->_iTail; // Snapshot index affected by irq
-    if (_tx_buffer->_iHead >= tail)
-        return SERIAL_BUFFER_SIZE - 1 - _tx_buffer->_iHead + tail;
-    return tail - _tx_buffer->_iHead - 1;
-}
+int HardwareSerial::availableForWrite(void) { return 1; }
 
 int HardwareSerial::peek(void) {
     if (_rx_buffer->_iHead == _rx_buffer->_iTail)
@@ -144,63 +138,21 @@ int HardwareSerial::read(void) {
 }
 
 void HardwareSerial::flush(void) {
-    while (_tx_buffer->_iHead != _tx_buffer->_iTail)
-        ; // wait for transmit data to be sent
 
     while (XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel) ==
            XMC_USIC_CH_TBUF_STATUS_BUSY)
         ;
 }
 
 size_t HardwareSerial::write(const uint8_t uc_data) {
-// Is the hardware currently busy?
-#if defined(SERIAL_USE_U1C1)
-    if (_tx_buffer->_iTail != _tx_buffer->_iHead)
-#else
-    if ((XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel) ==
-         XMC_USIC_CH_TBUF_STATUS_BUSY) ||
-        (_tx_buffer->_iTail != _tx_buffer->_iHead))
-#endif
-    {
-        // If busy we buffer
-        int nextWrite = _tx_buffer->_iHead + 1;
-        if (nextWrite >= SERIAL_BUFFER_SIZE)
-            nextWrite = 0;
-
-        // This should always be false but in case transmission is completed before buffer, we need
-        // to reenable IRQ
-        if (XMC_USIC_CH_GetTransmitBufferStatus(_XMC_UART_config->channel) !=
-            XMC_USIC_CH_TBUF_STATUS_BUSY) {
-            XMC_UART_CH_EnableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
-            XMC_UART_CH_Transmit(_XMC_UART_config->channel,
-                                 _tx_buffer->_aucBuffer[_tx_buffer->_iTail]);
-            _tx_buffer->_iTail++;
-            if (_tx_buffer->_iTail >= SERIAL_BUFFER_SIZE)
-                _tx_buffer->_iTail %= SERIAL_BUFFER_SIZE; // If iTail is larger than Serial Buffer
-                                                          // Size calculate the correct index value
-        }
-
-        unsigned long startTime = millis();
-        while (_tx_buffer->_iTail == nextWrite) {
-            if (millis() - startTime > 1000) {
-                return 0; // Spin locks if we're about to overwrite the buffer. This continues once
-                          // the data is
-                          // sent
-            }
-        }
-
-        _tx_buffer->_aucBuffer[_tx_buffer->_iHead] = uc_data;
-        _tx_buffer->_iHead = nextWrite;
-    } else {
-        // Make sure TX interrupt is enabled
-        XMC_UART_CH_EnableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
-        // Bypass buffering and send character directly
-        XMC_UART_CH_Transmit(_XMC_UART_config->channel, uc_data);
-    }
+    // For sending, write immediately
+    // This API already have a check for available buffer
+    XMC_UART_CH_Transmit(_XMC_UART_config->channel, uc_data);
     return 1;
 }
 
 void HardwareSerial::IrqHandler(void) {
+    // Receive data Interrupt handler
     uint32_t status = XMC_UART_CH_GetStatusFlag(_XMC_UART_config->channel);
 
     // Did we receive data?
@@ -214,24 +166,6 @@ void HardwareSerial::IrqHandler(void) {
                (USIC_CH_RBUFSR_RDV0_Msk | USIC_CH_RBUFSR_RDV1_Msk))
             _rx_buffer->store_char(XMC_UART_CH_GetReceivedData(_XMC_UART_config->channel));
     }
-
-    // Do we need to keep sending data?
-    if ((status & XMC_UART_CH_STATUS_FLAG_TRANSMIT_BUFFER_INDICATION) != 0U) {
-        XMC_UART_CH_ClearStatusFlag(_XMC_UART_config->channel,
-                                    XMC_UART_CH_STATUS_FLAG_TRANSMIT_BUFFER_INDICATION);
-
-        if (_tx_buffer->_iTail != _tx_buffer->_iHead) {
-            XMC_UART_CH_Transmit(_XMC_UART_config->channel,
-                                 _tx_buffer->_aucBuffer[_tx_buffer->_iTail]);
-            _tx_buffer->_iTail++;
-            if (_tx_buffer->_iTail >= SERIAL_BUFFER_SIZE)
-                _tx_buffer->_iTail %= SERIAL_BUFFER_SIZE; // If iTail is larger than Serial Buffer
-                                                          // Size calculate the correct index value
-        } else {
-            // Mask off transmit interrupt so we don't get it any more
-            XMC_UART_CH_DisableEvent(_XMC_UART_config->channel, XMC_UART_CH_EVENT_TRANSMIT_BUFFER);
-        }
-    }
 }
 
 //****************************************************************************